1. Field of the Invention
This invention relates to flying or floating craft and to devices which utilize a flowing fluid or movement of a body in fluid to create a rotation and/or lift or thrust.
2. Description of the Prior Art
Helicopters were commonly provided with an autorotation arrangement. However, the descending speed of the helicopter in autorotation is rather high. The "descent-speed slow down"-maneuver is a delicate procedure which often fails and the helicopter crashes.
The trend in development of helicopters is presently to reduce the weights. Also the weights of the rotors becomes reduced. That reduces as a side effect the time of the landing maneuver in autorotation and thereby increases the chance of failure of the landing maneuver, whereby the likeliness of a crash increases, when the engine of the helicopter fails.
In motor powered gliders it was custom in the former art to swing a motordriven propeller into and out of the craft, when a change-over from motorless gliding to powered gliding and vice versa was desired. The swing out of the propeller resulted in a negative influence on the flight path of the glider. The sudden appearance and disapparance of the drag of the propeller brought a negative influence on the speed and stability of the glider in the surrounding air.